This proposal describes the development of a personal wear badge for the accumulated exposure detection of benzene vapor. The badge consists of small sections of optical fiber that have been coated with a membrane specific for the adsorption of benzene vapor. After exposure the badge is placed in a Fourier Transform Infrared (FTIR) spectrometer and the infrared spectra of the surface derivative of benzene is determined. The quantitative exposure levels are determined by the peak intensities after first having been standardized. The sensor can be used again and cumulative exposure determined as a function of time. These new devices will allow rapid determination of exposure levels. Benzene vapor has primary adsorption bands in the mid-IR region. However, the concentration of benzene in the workplace is too low to be measured accurately with FTIR spectroscopy. The fiber surface modifications are based on the incorporation of benzene reactive compounds contained in a very thin, high surface area porous membrane coating applied to the fiber surface. The coating will enhance the concentration of benzene at the surface of the fiber. The surface coating technology will be developed and demonstrated on an active fiber system in the Phase I program. The badge will be engineered in such a way as to allow simple removal of the fiber module for direct insertion into the FTIR spectrometer.